Against the likelihood principle in visual form perception.

The likelihood principle, originally formulated by Helmholtz, states that the preferred perceptual organization of a sensory pattern reflects the most likely object or event. This principle of perceptual organization is compared with the minimum principle, which has its origin in the Gestalt tradition. This principle states that we see the simplest possible interpretation of a pattern, given the constraints inherent to the perceptual system. We argue that, as far as perception of visual form is concerned, the likelihood criterion is untenable as a criterion on which the preference for one interpretation over another could be based. Our main argument is that the likelihood principle implicitly starts from interpretations of patterns, whereas it is supposed to explain the existence of those interpretations in the first place. In our view, the likelihood of an interpretation is merely one consequence of the simplicity of the interpretation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When writing impairs reading: Letter perception’s susceptibility to motor interference.

The effect of writing on the concurrent visual perception of letters was investigated in a series of studies using an interference paradigm. Participants drew shapes and letters while simultaneously visually identifying letters and shapes embedded in noise. Experiments 1–3 demonstrated that letter perception, but not the perception of shapes, was affected by motor interference. This suggests a strong link between the perception of letters and the neural substrates engaged during writing. The overlap both in category (letter vs. shape) and in the perceptual similarity of the features (straight vs. curvy) of the seen and drawn items determined the amount of interference. Experiment 4 demonstrated that intentional production of letters is not necessary for the interference to occur, because passive movement of the hand in the shape of letters also interfered with letter perception. When passive movements were used, however, only the category of the drawn items (letters vs. shapes), but not the perceptual similarity, had an influence, suggesting that motor representations for letters may selectively influence visual perception of letters through proprioceptive feedback, with an additional influence of perceptual similarity that depends on motor programs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Geometric psychology generates the visual Gestalt.

Discusses an appropriate theoretical structure for the gestalt principles of visual form perception that is consistent with anatomical and neurophysiological knowledge and builds positively on it. It is suggested that much is known about the detailed psychophysics and physiology of mammalian visual systems, but there has been little study of the ways local processes in the visual system work cooperatively to produce the global phenomena of perception. The gestalt psychologists demonstrated perceptual organization but were hindered in their theorizing by the primitive knowledge at that time of how the brain operates and an inadequate model of cortical function. Recent discoveries in visual anatomy and physiology suggest that brain functions can be modeled in terms of one or more differentiable topological structures. Discussed are the visual manifold; holonomy, integrability, and visual contours; transversality and the principle of transverse control; interlude; and relation to the visual gestalt. It is concluded that (1) all the elements of a differential geometric structure can be identified within the primary visual processing system and (2) the major gestalt laws of perceptual organization follow naturally from the mathematical structure. (French abstract) (4 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Theoretical implications of the mnemonic benefits of perceptual interference.

How should interfering with the perception of items during study affect memory for those items? Recent research by J. Nairne (see, PA, Vol 76:7468) and E. Hirshman and N. Mulligan (see record 1991-26469-001) has demonstrated that backward pattern masking during study enhances later memory. This article examines whether traditional explanations of encoding benefits, including rehearsal, visual distinctiveness, and encoding effort, can account for this result. No evidence was found for any of these hypotheses. An explanation that focuses on the compensatory processing of higher level perceptual representations is proposed. This explanation provides a plausible explanation of the results of 7 experiments. The article concludes with a discussion of the implications of the explanation for perceptual priming and other manipulations of perceptual interference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gestalt principles in the control of motor action.

We argue that 4 fundamental gestalt phenomena in perception apply to the control of motor action. First, a motor gestalt, like a perceptual gestalt, is holistic in the sense that it is processed as a single unit. This notion is consistent with reaction time results indicating that all gestures for a brief unit of action must be programmed prior to initiation of any part of the movement. Additional reaction time results related to initiation of longer responses are consistent with processing in terms of a sequence of indivisible motor gestalts. Some actions (e.g., many involving coordination of the hands) can be carried out effectively only if represented as a unitary gestalt. Second, a perceptual gestalt is independent of specific sensory receptors, as evidenced by perceptual constancy. In a similar manner a motor gestalt can be represented independently of specific muscular effectors, thereby allowing motor constancy. Third, just as a perceptual pattern (e.g., a Necker cube) is exclusively structured into only 1 of its possible configurations at any moment in time, processing prior to action is limited to 1 motor gestalt. Fourth, grouping in apparent motion leads to stream segregation in visual and auditory perception; this segregation is present in motor action and is dependent on the temporal rate. We discuss congruence of gestalt phenomena across perception and motor action (a) in relation to a unitary perceptual–motor code, (b) with respect to differences in the role of awareness, and (c) in conjunction with separate neural pathways for conscious perception and motor control. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Awards for Distinguished Scientific Contributions 1986: Gunnar Johansson.

Gunnar Johansson is one of the 1986 recipients of the Awards for Distinguished Scientific Contributions. Johansson receives this award because of his "penetrating theoretical insights into human visual perception, combined with ingenious and creative experimental research. His analysis of how environmental regularities are exploited by perceptual decoding principles anticipated current thinking about constraints and inferential processors. His experimental studies have provided much of the foundation for our understanding of motion and depth perception. Together with his students, he developed a substantial body of innovative research on perceptual vector analysis and on the perception of minimal events, biological motion, nonrigid motion, self-motion, and natural motions. His advanced thinking provides continuing leadership and inspiration for current researchers in visual perception." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Similarity comparisons with remembered and perceived magnitudes: memory psychophysics and fundamental measurement

At the outset, subjects learned to associate a label with each element in a set of perceptual magnitudes (visual extents), using traditional paired-associate learning methods. Subsequently, on some trials, subjects indicated which pair of two pairs of labels corresponded to the more similar perceptual referents, and, on other trials, they selected the more dissimilar pair. It is shown that these similarity comparisons satisfy the axioms (transitivity and intradimensional subtractivity) necessary to conclude that they are based on computation of the difference of the differences of analogue-based interval scale representations. The findings also permitted refutation of the idea that memory for elementary percepts arises from their reperception. Notably, the memory exponent was 0.697, but the perception exponent was 0.546, and the reperception idea requires that the memory exponent be the square of the perception exponent (0.546(2) = 0.298). Symbolic distance effects and enhanced response time-based semantic congruity effects, typically found with binary comparisons, extend the range of commonalties found between perceptual and memory psychophysics.     

Electrophysiological evidence for a shared representational medium for visual images and visual percepts.

Systematic effects of imagery on visual signal detection performance have been used to argue that imagery and the perceptual processing of stimuli interact at some common locus of activity (Farah, 1985). However, such a result is neutral with respect to the question of whether the interaction occurs during modality-specific visual processing of the stimulus. If imagery affects stimulus processing at early, modality-specific stages of stimulus representation, this implies that the shared stimulus representations are visual, whereas if imagery affects stimulus processing only at later, amodal stages of stimulus representation, this implies that imagery involves more abstract, postvisual stimulus representations. To distinguish between these 2 possibilities, we repeated the earlier imagery-perception interaction experiment while recording event-related potentials (ERPs) to stimuli from 16 scalp electrodes. By observing the time course and scalp distribution of the effect of imagery on the ERP to stimuli, we can put constraints on the locus of the shared representations for imagery and perception. An effect of imagery was seen within 200 ms following stimulus presentation, at the latency of the 1st negative component of the visual ERP, localized at the occipital and posterior temporal regions of the scalp, that is, directly over visual cortex. This finding supports the claim that mental images interact with percepts in the visual system proper and hence that mental images are themselves visual representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reuniting perception and conception

Work in philosophy and psychology has argued for a dissociation between perceptually-based similarity and higher-level rules in conceptual thought. Although such a dissociation may be justified at times, our goal is to illustrate ways in which conceptual processing is grounded in perception, both for perceptual similarity and abstract rules. We discuss the advantages, power and influences of perceptually-based representations. First, many of the properties associated with amodal symbol systems can be achieved with perceptually-based systems as well (e.g. productivity). Second, relatively raw perceptual representations are powerful because they can implicitly represent properties in an analog fashion. Third, perception naturally provides impressions of overall similarity, exactly the type of similarity useful for establishing many common categories. Fourth, perceptual similarity is not static but becomes tuned over time to conceptual demands. Fifth, the original motivation or basis for sophisticated cognition is often less sophisticated perceptual similarity. Sixth, perceptual simulation occurs even in conceptual tasks that have no explicit perceptual demands. Parallels between perceptual and conceptual processes suggest that many mechanisms typically associated with abstract thought are also present in perception, and that perceptual processes provide useful mechanisms that may be co-opted by abstract thought.     

Object trimming: When masking dots alter rather than replace target representations.

Five experiments demonstrate that when dots appear beside a briefly presented target object, and persist on view longer than the target, the flanked object is perceptually altered by the dots. Three methods are used to explore this object trimming effect. Experiments 1–3 assess participants’ conscious reports of trimmed digits, Experiment 4 uses repetition priming to explore the target representation, and Experiment 5 examines the perception of apparent motion in trimmed targets. Results of all three methods indicate that object trimming is influenced by mechanisms of perceptual grouping that operate on target representations prior to conscious access. Separate contributions from visual crowding and backward masking are also identified. These results imply that common-onset masking does not always result from the target being substituted by the mask, but that target and mask can sometimes maintain separate mental representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is visual imagery really visual? Overlooked evidence from neuropsychology.

Does visual imagery engage some of the same representations used in visual perception? The evidence collected by cognitive psychologists in support of this claim has been challenged by three types of alternative explanation: Tacit knowledge, according to which subjects use nonvisual representations to simulate the use of visual representations during imagery tasks, guided by their tacit knowledge of their visual systems; experimenter expectancy, according to which the data implicating shared representations for imagery and perception is an artifact of experimenter expectancies; and nonvisual spatial representation, according to which imagery representations are partially similar to visual representations in the way they code spatial relations but are not visual representations. This article reviews previously overlooked neuropsychological evidence on the relation between imagery and perception, and discusses its relative immunity to the foregoing alternative explanations. This evidence includes electrophysiological and cerebral blood flow studies localizing brain activity during imagery to cortical visual areas, and parallels between the selective effects of brain damage on visual perception and imagery. Because these findings cannot be accounted for in the same way as traditional cognitive data using the alternative explanations listed earlier, they can play a decisive role in answering the title question. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coordinate transformations in object recognition.

A basic problem of visual perception is how human beings recognize objects after spatial transformations. Three central classes of findings have to be accounted for: (a) Recognition performance varies systematically with orientation, size, and position; (b) recognition latencies are sequentially additive, suggesting analogue transformation processes; and (c) orientation and size congruency effects indicate that recognition involves the adjustment of a reference frame. All 3 classes of findings can be explained by a transformational framework of recognition: Recognition is achieved by an analogue transformation of a perceptual coordinate system that aligns memory and input representations. Coordinate transformations can be implemented neurocomputationally by gain (amplitude) modulation and may be regarded as a general processing principle of the visual cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eleanor J. Gibson: Learning to perceive and perceiving to learn.

E. Gibson essentially defined the domain of perceptual learning, which includes both improvement in perception as a function of experience and learning and acquisition of knowledge as a function of changes in perception. In her view, differentiation, as opposed to association, is the process underlying perceptual development as well as perceptual learning. She considered perceptual development to be an important aspect of cognitive development. To a considerable degree, children's acquisition of knowledge and their increasingly complex conceptual sophistication can be attributed to their ability to detect more and more meaningful aspects of the rich stimulation impinging on them. This theoretical analysis was instantiated in empirical research on a wide range of topics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of early experience on children's recognition of facial displays of emotion.

The present research examines visual perception of emotion in both typical and atypical development. To examine the processes by which perceptual mechanisms become attuned to the contingencies of affective signals in the environment, the authors measured the sequential, content-based properties of feature detection in emotion recognition processes. To evaluate the role of experience, they compared typically developing children with physically abused children, who were presumed to have experienced high levels of threat and hostility. As predicted, physically abused children accurately identified facial displays of anger on the basis of less sensory input than did controls, which suggests that physically abused children have facilitated access to representations of anger. The findings are discussed in terms of experiential processes in perceptual learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working Memory Consolidation Is Abnormally Slow in Schizophrenia.

This study reports evidence that patients with schizophrenia demonstrate a slowing of working memory (WM) consolidation, which is the process of transforming transient perceptual representations into durable WM representations. Sixteen schizophrenia patients and 16 healthy control participants performed a task measuring the visual WM consolidation rate in a change-detection paradigm. A target display containing 3 colored squares was followed by a variable delay of 17-483 ms, a pattern mask, and then a test stimulus. This pattern mask does not interfere with perception but disrupts WM consolidation. Control participants reached no-mask performance by 250 ms, indicating completed WM consolidation, whereas patients failed to reach no-mask performance by 483 ms. Slowed consolidation may play an important and largely unrecognized role in schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Single units and conscious vision

Figures that can be seen in more than one way are invaluable tools for the study of the neural basis of visual awareness, because such stimuli permit the dissociation of the neural responses that underlie what we perceive at any given time from those forming the sensory representation of a visual pattern. To study the former type of responses, monkeys were subjected to binocular rivalry, and the response of neurons in a number of different visual areas was studied while the animals reported their alternating percepts by pulling levers. Perception-related modulations of neural activity were found to occur to different extents in different cortical visual areas. The cells that were affected by suppression were almost exclusively binocular, and their proportion was found to increase in the higher processing stages of the visual system. The strongest correlations between neural activity and perception were observed in the visual areas of the temporal lobe. A strikingly large number of neurons in the early visual areas remained active during the perceptual suppression of the stimulus, a finding suggesting that conscious visual perception might be mediated by only a subset of the cells exhibiting stimulus selective responses. These physiological findings, together with a number of recent psychophysical studies, offer a new explanation of the phenomenon of binocular rivalry. Indeed, rivalry has long been considered to be closely linked with binocular fusion and stereopsis, and the sequences of dominance and suppression have been viewed as the result of competition between the two monocular channels. The physiological data presented here are incompatible with this interpretation. Rather than reflecting interocular competition, the rivalry is most probably between the two different central neural representations generated by the dichoptically presented stimuli. The mechanisms of rivalry are probably the same as, or very similar to, those underlying multistable perception in general, and further physiological studies might reveal much about the neural mechanisms of our perceptual organization.     

Menstrual cycle phase and mood effects on perceptual asymmetry

Several studies have reported shifts in perceptual asymmetry during the menstrual cycle, but the potential confounding effect of mood changes has been largely ignored. In this study, 24 female subjects completed four visual laterality tasks and a mood questionnaire at three phases of the cycle. Results indicate no overall effect of cycle phase on any of the asymmetry or mood scores. However, results revealed significant associations between affect and perceptual asymmetry on a face perception task. Implications for mood effects on perceptual asymmetry and future research on cycle-related shifts in asymmetry are discussed.     

To what extent do Gestalt grouping principles influence tactile perception?

Since their formulation by the Gestalt movement more than a century ago, the principles of perceptual grouping have primarily been investigated in the visual modality and, to a lesser extent, in the auditory modality. The present review addresses the question of whether the same grouping principles also affect the perception of tactile stimuli. Although, to date, only a few studies have explicitly investigated the existence of Gestalt grouping principles in the tactile modality, we argue that many more studies have indirectly provided evidence relevant to this topic. Reviewing this body of research, we argue that similar principles to those reported previously in visual and auditory studies also govern the perceptual grouping of tactile stimuli. In particular, we highlight evidence showing that the principles of proximity, similarity, common fate, good continuation, and closure affect tactile perception in both unimodal and crossmodal settings. We also highlight that the grouping of tactile stimuli is often affected by visual and auditory information that happen to be presented simultaneously. Finally, we discuss the theoretical and applied benefits that might pertain to the further study of Gestalt principles operating in both unisensory and multisensory tactile perception. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Neglected developmental variables in the study of species identification in birds.

Considers that a question of the highest developmental and perceptual significance launched the experimental analysis of imprinting: How do animals come to identify members of their own species in the course of ontogeny? As laboratory research on imprinting in birds has become more and more removed from that primary question, it has neglected certain fundamental natural history and neuroembryological facts which are basic to the study of the development of species-specific perception in birds and perhaps other animals. These problems are discussed in the context of an empirical review of the development of the auditory and visual components of species identification in wild and domestic ducklings. (37 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)